The Ischemic Optic Neuropathy Decompression Trial (IONDT) is a five year study designed to assess the safety and efficacy of optic nerve sheath decompression surgery (ONDS) for non-arteritic ischemic optic neuropathy, diagnosed within one month of onset of visual symptoms. A standardized, common protocol for treatment and data collection will be used by all centers. This multicenter, randomized clinical trial is designed to compare differences in patients randomized to one of two treatment groups as follows: Treatment Group Treatment Sequences No. of Patients 1. Test Treatment Optic Nerve Sheath 150 Decompression 2. Control Treatment Standard Medical Care 150 (no surgery) The primary hypothesis to be addressed by this trial is whether treatment with ONDS is more effective than standard care in (1) restoring or (2) maintaining central visual acuity in patients with NAION? The primary outcome for this trial (change in visual acuity) will be measured using the New York Lighthouse chart. A gain of three or more lines of visual acuity (doubling of the visual angle) will be considered improvement. Secondary outcomes include change in peripheral visual function (using standard Goldmann perimetry) and incidence ophthalmic and systemic complications. Patients will be recruited over a two year period and followed for a minimum of one year. Study Centers will include a Chairman's Center, 26 Clinical Centers, and centralized facilities, including a Coordinating Center, a Reading Center, and a Project Office at the National Eye Institute.